1. Field of the Invention
This invention relates to a material separation apparatus and method and more particularly to an improved froth flotation separation apparatus and method.
2. Description of the Prior Art
In a known flotation separation process which is utilized for example in separating a valuable mineral from its ore or gangue, the ore is initially crushed to a fine powder and is then mixed with a liquid such as water to form a thin, flowable mud or slurry. Wetting agents are added to the slurry which selectively wet the surface of the valuable mineral sought to be separated but do not affect the less valuable ore components such as rock, clay, sand, etc. This slurry is introduced to a vessel of a flotation separation cell where it is both agitated and aerated. Air is dispersed in the agitated slurry and valuable mineral particles which have been wetted by the added agent attach to small air bubbles and accumulate in a froth or foam near the top of the slurry mass. The froth is then separated by overflowing a weir or separation lip in a wall of the vessel and is accumulated and dried. Tailings of residue components of rock, clay, sand, etc. flow to an adjacent separation cell or are withdrawn from a bottom of the cell.
In one form of flotation cell, a rotor-stator assembly is positioned below the cell slurry level near a bottom surface of the vessel. The rotor comprises a plurality of radially extending blade members which are rotated in a central space or cavity defined by an annular array of stator blades. Circular motion of the rotor blades agitates and establishes a flow of slurry into which air is dispersed.
In a prior form of rotor, each rotor blade member consists of a pair of juxtaposed closely spaced plates. Dispersal of air in the slurry is accomplished by flowing a stream of air between the juxtaposed plates along their length and discharging the air into the moving slurry at outer edges of the blades. Air dispersal has also been accomplished by conveying a stream of air to a point below the rotor and discharging it at that location. In still another arrangement, the air is dispersed from standpipes positioned near the surface of the slurry and adjacent the rotor.
The dispersement of air into the slurry has an important bearing on the efficiency of formation of air particles or bubbles in the slurry and ultimately on the purity and percentage of the recovery value of the valuable mineral. The configuration of the cell and its rotor and stator components has an equally important bearing on the required operating energy and efficiency of operation of the cell.